Because salmon live both in salt and freshwater, they have physical (different urine concentrations) and behavioral (drinking more or less water) adaptations to maintain osmolality. In this osmoregulation video, the instructor reviews osmosis, hypertonic, isotonic, and hypotonic solutions. Viewers then explore how freshwater and saltwater fish maintain osmolarity. The video finishes by taking a look at how kidneys act as an osmoregulatory organ.